Three-dimensional (3D) printing, also known as additive manufacturing (AM), is growing in popularity. As technology progresses, different methods of forming 3D models through additive manufacturing technology have been proposed. Generally, additive manufacturing technology uses a design information of 3D models from software such as computer-aided design (CAD) to be converted to multiple thin cross sections (quasi-two-dimensional) continuously stacked. One of the common methods for 3D printing is to use powders and solidify them to the desired shape. Examples of prior 3D printing methods and systems include for example selective laser melting (SLM) or DMLS (Direct Metal Laser Sintering) comprising high power-density laser for melting and fusing metallic or polymers powders together.
In recent years, electrophotography methods and systems used in two-dimensional (2D) printing were implemented in 3D printing methods. In accordance with the prior art (2D) printing electrophotography systems include a conductive support drum coated with a photoconductive material, where latent electrostatic images are formed by uniformly charging and then image-wise exposing the photoconductive layer by an optical source. The latent electrostatic images are then moved to a developing station where toner is applied to uncharged areas of the photoconductive insulator to form visible images. The formed toner images are then transferred to substrates (e.g., printing paper) and affixed to the substrates with heat or pressure.
An example of additive manufacturing system for printing a three-dimensional part using electrophotography is illustrated in U.S. Pat. No. 8,488,994 entitled “Electrophotography-based additive manufacturing system with transfer-medium service loops”. The additive manufacturing system including a rotatable photoconductor component, a development station configured to develop layers of a material on a surface of the rotatable photoconductor component, a rotatable transfer medium configured to receive the developed layers from the surface of the rotatable photoconductor component, and a platen configured to receive the developed layers from the rotatable transfer medium in a layer-by-layer manner. The additive manufacturing system also includes a plurality of service loops configured to move portions of the rotatable transfer medium at different line speeds while maintaining a net rotational rate of full rotations of the rotatable transfer medium at a substantially steady state.
FIG. 1 illustrates a Selective laser melting (SLM) system 100 for dispensing materials in the form of powder in a 3D printing system, in accordance with the prior art. The system 100 comprises a fusing container 101 a powder container 102 and a laser head 103 configured to emit a laser beam for fusing a powder layer image dispensed from the powder container 102 to the fusing container 101. Specifically, in operation once a fusing process of a single layer (e.g. the top layer) is completed a carrier plate 106 (holding the powder 104 and the printed model 105) moves down while the carrier plate 108 moves up and a roller 109 or plate dispenses a layer of powder from powder container 102 to container 101 to be fused by the laser head 103.